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Old Jan 15, 2007, 06:01 PM
Speedy Tree Surgeon
Tiverton,Devon,UK
Joined May 2006
680 Posts
Help!
Whats the best way to join this fuse together?

Hi guys,
I've got this plug i'm working on and i'm getting to a stage where i need to start thinking about the best way to join the two halves together before making the mould.

I've thought about maybe using a joggle plate to create a step as there isn't much room or open spaces for a taped seam

On the fin i was thinking of joining with resin and cotton flock mix like they did on a german f5b wing.They put the mix in a pipeing bag and put bead around the seam before closeing the mould together.

Anyone got any ideas on how this could be done as the only opening i want is in the nose section and only a small hole of about 8-10mm in the tail end.

The fuse is a about 29" long and max diameter is 2".

Tim
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Old Jan 15, 2007, 07:48 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,584 Posts
Tough question, but I like the looks of that fuse....
Will it also get a slip on nose cone?

Target
PS. You may have better luck in the Composites forum, I'd post a link to this thread there, if you haven't already.
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Old Jan 15, 2007, 07:54 PM
Speedy Tree Surgeon
Tiverton,Devon,UK
Joined May 2006
680 Posts
Thanks Target,

Yes it going to have a slip on nose cone,that was the first mould i made on this project before i re-modeled the fuz.

I have the same question going on in my build thread in the composite fabrication forum.

2 forums are better than 1

link to build threadhttp://www.rcgroups.com/forums/showthread.php?t=570223

Cheers

Tim
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Last edited by avago; Jan 18, 2007 at 05:43 PM.
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Old Jan 15, 2007, 08:19 PM
No fuse too fat
slopeiron's Avatar
USA, CA, Redondo Beach
Joined Apr 2002
3,879 Posts
Well, here is what I plan to do with my next mold. I will start with what you have so far - the plug with the fin on it. Then I will make a mold of just the fin, including the fillet section where it blends into the fuse. Once I have the fin mold, I will cut the fin off the plug. Next, I will make a fin from the mold and use that to build a step-down on the plug so that the fin will fit perfectly on the finished fuse.

If you make the fin a separate mold, you can leave an opening in the step-down area to give you access for seaming. It will be covered up when you put the fin on. If the step-down is 1/4" or so, that would give you plenty of surface for some goop to really hold it tight. Then you could just lay a layer of some 1oz cloth over the seam on the outside, a little filler over that and you would never know it was two pieces.

Might sound like a lot of work, but it would make the fuses much easier to layup. All my planes up to this point have had molded fins and they are a pain to do.

BTW, fuse looks cool. Looking forward to seeing the finished plane.

Edit:
One question though. Why not leave an opening in the wing saddle also to help with seaming?

Russ.
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Old Jan 15, 2007, 08:26 PM
Speedy Tree Surgeon
Tiverton,Devon,UK
Joined May 2006
680 Posts
Hi russ,
Thanks for the info.I never thought of doing it that way ,i was trying to keep it all in one piece so i could use pigmented gelcoat for a nice finish and no filling or painting to do,but i might not have a choice in it.

I might have to put a cutout in the wing saddle for more access or go with your idea.

The reason i didn't want a cutout in the wing saddle was for extra strength,that was where the 2 weak points were on the original.

Cheers

Tim
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Last edited by avago; Jan 15, 2007 at 08:43 PM.
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Old Jan 15, 2007, 08:51 PM
No fuse too fat
slopeiron's Avatar
USA, CA, Redondo Beach
Joined Apr 2002
3,879 Posts
<deleted>
Just saw your comment above about having a slip on nose cone.
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Last edited by slopeiron; Jan 15, 2007 at 10:42 PM.
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Old Jan 15, 2007, 09:03 PM
No fuse too fat
slopeiron's Avatar
USA, CA, Redondo Beach
Joined Apr 2002
3,879 Posts
Quote:
Originally Posted by avago
i was trying to keep it all in one piece so i could use pigmented gelcoat for a nice finish and no filling or painting to do...
That's another story. Glassing and sanding on the outside is pretty much out if that's your goal.
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Old Jan 15, 2007, 09:39 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,584 Posts
Quote:
Originally Posted by avago
The reason i didn't want a cutout in the wing saddle was for extra strength,that was where the 2 weak points were on the original.

Cheers

Tim

You can always close it back up with a piece of pre curved composite, molded against the wing, or a piece of 1/32" ply...

You are right, though, the fuses are much stronger with the saddle only opened enough for the servo wires.

G/Luck,

Target
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Old Jan 15, 2007, 10:22 PM
find me @samotage
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Melbourne Australia
Joined Jul 2005
8,362 Posts
Hey Tim,

Nice looking plug!

What is the diameter of the front opening? It looks like some motor type mount to me? IMO I rekon this is big enought to poke a wet seam roller into it to roller down the top and bottom seams real easily. The one I have is a metere long piece of 3.5mm (or so) dia piano wire, with an L bend at the end and a small grooved roller 8-10mm wide, and 10mm in diameter stuck on the end. If I keep it clean from resin, I can poke this little prong just about anywhere. For this mold, it would easlily do the top and bottom, all from the front opening.

For the fin, the whole thing can be simply molded up in one hit. Just use some cabosilised resin with some flocks if you feel like it, to run a bead around the edges of the fin and smoosh it together. Piece of cake! It helps to have alognment pins in the mold to make it come together - so use a parting tray to make your your mold.

Sam,
and his sticky finger.
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Old Jan 16, 2007, 01:57 AM
chetosmachine's Avatar
Madrid, Spain
Joined Sep 2004
1,102 Posts
With a 8-10 mm hole on the back of the fuse, you can do a wet seam on the fuse and seam the fin with some epoxy+microballons+chopped fibers.
You can use a small, 4mm steel rod with a smooth end (a big drop of 5 minute epoxy works well for this, then some sand paper to make it really smooth) to push the seam when the mold is closed.
Regards,
Chets
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Last edited by chetosmachine; Jan 16, 2007 at 01:12 PM.
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Old Jan 16, 2007, 10:14 AM
Registered User
United States, OR, Tualatin
Joined Apr 2005
2,479 Posts
Seams are difficult

This plane looks on the small side, like maybe a speed 400 racer (F4D?). If you are going to glue the wing onto the fuse, then the wing saddle opening won't really matter. Open for construction and to install gear, then closed once the wing is on. For balancing, hold the wing on with tape.

I am thinking of making an "H" section that I can slip each side of the fuse into. After the epoxy has hardned, I'll cut off the outside flange and sand it down before painting. Can't paint in the mold, but I want to install some former bulk heads for my ballast tube, so that is the trade off. My rudder fin will be a separate piece, so I'll be doing a lot of finish work before painting. The fin will plug into (2) carbon fiber rods that go into bras sleeves in the fin.

Good luck. Plug looks great
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Last edited by TomFlyer; Jan 16, 2007 at 10:15 AM. Reason: spelling
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Old Jan 16, 2007, 07:04 PM
Speedy Tree Surgeon
Tiverton,Devon,UK
Joined May 2006
680 Posts
Quote:
Originally Posted by samotage
Hey Tim,

Nice looking plug!

What is the diameter of the front opening? It looks like some motor type mount to me? IMO I rekon this is big enought to poke a wet seam roller into it to roller down the top and bottom seams real easily. Sam,
and his sticky finger.

Hi Sam

The opening at the front is about 35 x 140mm where the rx/bats gonna go. Theres no motor on this plane but the flat on the nose is clearance for the slip on cone.

I'm going to use a parting board and dowels for the mould.I've been trying to get hold of some of these at a reasonable price cos they do 2 in 1 jobs
http://www.henleycraft.co.uk/GRP%20M...tle%20Page.htm

Have i got this right with the wet seam?

Trim 1 mould half flush,trim other half slightly proud , put the 2 together with a bit of resin on the seam and roll down flat?

Cheers

Tim and his 100 gloves to avoid sticky fingers this time
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Old Jan 16, 2007, 07:12 PM
Speedy Tree Surgeon
Tiverton,Devon,UK
Joined May 2006
680 Posts
Quote:
Originally Posted by chetosmachine
With a 8-10 mm hole on the back of the fuse, you can do a wet seam on the fuse and seam the fin with some epoxy+microballons+chopped fibers.
You can use a small, 4mm steel rod with a smooth end (a big drop of 5 minute epoxy works well for this, then some sand paper to make it really smooth) to push the seam when the mold is closed.
Regards,
Chets
Hi Chets,
I'm going to Avago at this wet seam thing as it seam to be what everyone has said.

The fin i'm going to do like what you said as i've seen this done for hollow wing joining in the Racketwurm vid and know it works.

Cheers

Tim
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Old Jan 16, 2007, 08:34 PM
find me @samotage
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Melbourne Australia
Joined Jul 2005
8,362 Posts
Hey Tim,

You are just about there mate. My tips are:

1. Use melamine cabinetry board for the parting board. This will require little wax to repel your mold.
2. Use plastic furniture leg proctector domes. Just stick 'em on the parting board to mold your locators in place.

3. For the wet seam, each half will have a lap poking out, top on one half bottom on the other. I mix up some runnyish cabosil/poxy and squirt from a plastic baggy bag along the mold side of the lap. Align and plop 'em down, it's real easy!

4. Then get in there with the roller on a poker and roll the seams flat.

Sam.
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Old Jan 17, 2007, 01:32 AM
built flown + crashed it
Pewsey, Great Britain (UK)
Joined Oct 2004
408 Posts
This should help you visulize how a wet seam layup works, like Sam says, easy when you know how!

http://www.valegliders.com/Workshop.htm
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